Substantially immobile people (i.e. wheelchair bound users) experience a great need for body supports that minimize development of decubitus ulcers (i.e. bedsores) caused by skin stress, that can occur during long periods of immobility, such as confinements to wheelchairs.
The common approach to addressing this need is usage of stress-absorbing and pressure dispersing materials, such as various gels and foams. Such cushions, of various shapes and sizes, are described in U.S. Pat. Nos. 7,216,388 and 5,444,881, for example.
Known seat cushions do not resolve the appearance of high pressure points along the surface of the cushions at locations varying from one user to another due to personal anatomy.
In other prior art devices, such as described in U.S. Pat. No. 5,191,752, the cushion is a sack filled with gel or another fluid-like substance. While such design provides relatively high shock-absorbency, it does not provide adequate anatomical support, moreover—it is prone to leaks.
Using gel materials themselves face user with many difficulties, for example, heat retention. During continuous periods of contact with user's body, the temperature and moisture in the contact areas between the gel-filled cushion and the user's body also increases. Risen material heat causes user discomfort and increases suffering caused by new and existing injuries, such as bedsores. Heat causes increased growth of bacteria in sored area, thus promoting infections and skin irritations. Another disadvantage is the relatively high weight of the gel materials themselves, while relative fragility.
Well known in the art alternative to use of gel materials is use of foam materials. However, using foam materials proves to be less than optimal as well. After many usage cycles, foam is taking compression set, losing cushion support benefit.
The problem of pressure relief was attempted to be resolved in numerous ways. For example, U.S. Pat. No. 5,193,237 discloses a pneumatic cushion having a number of separate air pockets arranged in a matrix. Reduced airflow and therefore reduced air pressure is periodically provided within the cushion so that each air sack will have reduced pressure for a predetermined period of time. A self-regulating air distribution is provided such that when the occupant shifts his/her weight so as to overcome the air pressure in a sack, the system automatically backflows air into that particular sack thereby cushioning the user. While providing seemingly adequate result, devices such as aforementioned provide expensive to manufacture and maintain solution.
Thus, there is a need to provide an improved anatomical support device that reduces shear forces and pressure on the upper legs and buttocks of a user and maximizes pressure relief, stability, comfort, durability and maintainability.